Screen changer

ABSTRACT

A screen changer wherein sealing pressure is obtained against a breaker plate and filter screen element by providing a screw adjustment from an external adapter which bears against a sealing bearing. The sealing bearing bears against a slide plate carrying the breaker plate to provide a simple and effective externally controllable sealing pressure engagement.

United States Patent 1191 Paquette Mar. 19, 1974 1 SCREEN CHANGER3,325,980 6/1967 Chameroy et al. 55/422 3,615,257 10/1971 Frost et a1210/447 X [75] Invent: Jame? Paquem, sierlmg 3,645,401 2/1972 Roberts210/232 Juncnon, Mass- 3.471.023 10/1969 Rosaen 210/236 x [73] Assignee:The Berlyn Corporation, Millbury,

Mass. Primary ExaminerSamih N. Zaharna 1 Assistant Examiner-Richard W.Burks [22] Filed 1972 Attorney, Agent, or Firm-Curtis, Morris & Safford[21] Appl. No.: 307,815

[57] ABSTRACT [52] US. Cl. 210/236, 210/447 [51] Int. Cl B0111 29/00 AScreen changer wherem Sealing pressure obtamed [58] Fiend of Search55/97 328 422 481 against a breaker plate and filter screen element by 26 providing a screw adjustment from an external adapter which bearsagainst a sealing bearing. The sealing 56] References Cited bearingbears against a slide plate carrying the breaker plate to provide asimple and effective externally con- UNITED STATES PATENTS trollablesealing pressure engagement. 565,972 8/1896 Fowler 210/447 X 2,244,5076/1941 Thomas 55/422 X 8 Claims, 3 Drawing Figures SCREEN CHANGER Thepresent invention relates to screen changers and more particularly thepresent invention relates to an improved manner of applying sealingpressure to screen changers.

In manufacturing operations such as plastic extrusion, fiber spinning orchemical processing where a mass of heat-softened material is worked, itis essential that contaminants in the materials be removed or filteredout prior to final processing. To such an end, apparatus such as filterscreens in the form of square mesh wire cloth or the like are interposedin the path of flow of the material to be filtered. The filtering mediumis supported by a backup or breaker plate provided with flow passagestherethrough so that material once it has been strained by the filtermedia flows through the breaker plate and out of the filtering apparatusfor further processing.

Because the filtering medium becomes clogged with contaminants after aperiod of use, it is necessary to change the screen element and,accordingly, most filter screen apparatuses have provision for rapidchange of the filter media.

The present invention relates to such an apparatus commonly known as ascreen changer. In screen changers it is necessary to provide a sealingpressure against the filter screen and breaker plate so that when thematerial to be filtered, which is commonly processed through a filterscreen changer under high pressure, is passed through the filter screenapparatus no leakage will occur. Sealing pressure must be applied duringperative state of the process and is maintained while a hydrauliccylinder moves the slide plate carrying the breaker plate to place afresh filter medium in the flow path of the material. In time the sealswear necessitating an adjustment.

At present, most filter screen changing apparatus use a complex threadedsleeve arrangement which is externally adjusted much like a threaded nutto apply sealing pressure against the breaker plate. Such threadedsleeves become inordinately large for large filter screen apparatus,must be very carefully machined and are therefore exceedingly expensiveto manufacture and require complex internal seal arrangements tocompensate for the movement of the sleeve.

Other designs utilize split bodies that are bolted together. These aredifficult to align properly, and more expensive to machine, take up morespace and sacrifice strength.

It is an object of the presentinvention to provide a filter screenchanging apparatus with an efficient and effective means for providingsealing pressure against the breaker plate.

A further object of the present invention is to provide a screen changerof the character described wherein sealing pressure against the breakerplate is accomplished with a simple sleeve bearing and threaded boltadjustment of an external adapter against the sleeve bearing.

It is also an object of the present invention to provide an improvedbreaker plate construction in a screen changing apparatus to improve theflow characteristics of the material being filtered.

These and other objects and advantagess of the present invention will bemore readily apparent after consideration of the following specificationtaken in conjunction with the accompanying drawing, in which:

FIG. 1 is a sectional view of the screen changer apparatus of thepresent invention;

FIG. 2 is an enlarged sectional view of a segment of the removable-typebreaker plate of the screen changing apparatus of the present invention;and

FIG. 3 is a plan view of the breaker plate of the present invention.

With reference to the drawing and particularly FIG. 1, a slide platescreen changer apparatus 10 is shown and includes a housing 12, which ispreferably a onepiece cast steel housing, provided with a cylindricalbore 14 disposed axially through the housing. A slide plate opening 116is also provided which may be rectangular in cross-section and which isformed laterally through the housing 12 perpendicular to the axis ofcylindrical bore 14.

A slide plate member 18 is provided within slide opening 16 and isadapted to be moved laterally within housing 12 whenever a screenchanging procedure is initiated. Slide plate 18 serves as a carrier forthe filtering medium 20 which is preferably a mesh screening materialhaving a circular configuration and carried within a circular opening 22in slide plate 18.

The flow of the material to be filtered is from left to right, as viewedin FIG. 1, and since the material is processed through housing 12 underhigh pressure, immediately behind the filtering medium 20 a backup orbreaker plate 24 is provided disposed within the slide plate 18. Thus,when the plastic material to be filtered is caused to flow throughhousing 12, the material is forced through the screening material 20which is mounted within a circular groove 21 in slide plate 18 andsupported by the backup or breaker plate 24 and through the breakerplate 24 through a plurality of flow passages 26 (see FIGS. 2 and 3)therethrough. The slide plate 18 is disposed within housing 112 duringfiltering operation by bolt members 28 and 30 disposed within boltreceiving apertures 32 and 34, respectively, in housing ll2 with each ofthe bolts being threadably engaged within a nut member 36 secured tohousing 12 so that the ends 38 and 40, respectively, of bolts 28 and 30bear against slide plate 18 to firmly position the slide plate withinthe housing 12.

While material such as a heat-softened plastic material is processedthrough the filtering apparatus, the material is forced to flow throughthe apparatus under high pressures. Consequently, provision must be madeto seal the material within the housing to preclude leakage.Accordingly, a seal in the form of a cylindrical sleeve bearing member42, which preferably is of an alloy such as Bernalloy is provided withincylindrical bore 114 on the upstream side of material flow. One end 44of the sleeve fits in abutting relationship against that segment of theslide plate 18 which overlies the screen 20 to confine the material tobe filtered within the cylindrical cavity 46 of sleeve 42. As long asthe sleeve 42 is maintained in abutting relationship against slide plate18 with sufficient force, an effective and tight seal is maintained sothat the material being filtered does not leak out of the housing 12through the slide opening 16.

To maintain the sleeve 42 in a pressure sealing relationship against theslide plate 18 a flanged adapter member 48 is provided. The adapter 48includes a cylindrical cavity 50 therethrough in register with bore 14through which the material to be filtered is caused to flow underpressure. One end 52 of adapter 48 is provided with a cylindricalindentation 54 to accommodate the free end 56 of sleeve 42. The adapter48 includes a flanged segment 58 provided with a plurality ofcircumferentially spaced bolt access bores 60 therethrough. A pluralityof threaded bolt members 62 are provided through the bolt access bores60 in flange 58 and into a plurality of threaded receiving bores 64 inhousing 12. Thus, the adapter member 48 maintains the sleeve 42 in tightabutting sealing relationship against slide plate 18 when the bolts 62are threadably engaged through the flange 58 and into the housing 12.

The downstream side, i.e. after the material has flowed through thefilter and breaker plate 24, is also sealed to preclude leakage ofafluid out of housing 12. On the downstream side a sleeve 66, which isalso preferably of an alloy such as Bernalloy, is provided. Sleeve 66includes a forward face 68 adapted to abut the breaker plate 24 insealing relationship provided with a conically shaped cavity 70 thereinterminating in a cylindrical through passage 72. The shape of the cavity70 is designed to channel the flow of material after it has passedthrough the breaker plate toward the centrally disposed flow passage 72.Sleeve 66 also includes an extending flange segment 74 at its other endwhich provides a shoulder 76 to sit in abutting relationship on the rearface 78 of the housing 12.

A downstream adapter segment 80 is also provided which includes aflanged segment 82 having a plurality of circumferentially spacedthreaded bolt receiving bores 84 therethrough. A plurality of threadedbolt members 86 are engaged through the bores 84 and into threadedreceiving bores 88 in the housing 12 and the adapter 80 is maintained insealing abutting relationship with sleeve 66 by tightening the bolts 84.

The adapter 84 also includes a cylindrical flow passage 88 therethroughwhich is in register with the flow passage 72 in sleeve 66 so thatmaterial which has been filtered by filter 20 flows under pressurethrough the breaker plate 24 and into the flow passages 72 and 88 untilit passes out of the filter apparatus to a die or other processing step.

Reference is now made to FIGS. 2 and 3 where the breaker plate 24 of thepresent invention is illustrated. The breaker plate 24 includes anupstream segment 90 which has a larger cross-sectional diameter than thedownstream segment 92 to form a shoulder 94 which sits in abuttingrelationship against a shoulder 96 (see FIG. 1) formed in the slideplate 18. Since the pressure causing the material to flow through thescreen 20 and breaker plate 24 is imparted from the upstream side, thebreaker plate assembly maintains its orientation within the slide plateduring operation because of the engagement of the shoulder 94.

Throughout the central portion of the breaker plate 24 the flow passages26 are formed as straight cylindrical openings through the breakerplate. The straight through openings include a counterbored segment 98at the upstream end which leads into the cylindrical segment 100. Theflared ends 98 minimize dead spots to preclude collection of theheat-softened material on the upstream side of the breaker plate andoffer a minimum resistance to the flow of the material through thepassages 26.

Because the flow of the material is drastically restricted immediatelyafter it emerges from the breaker plate on the downstream side, as thematerial flows through the conical depression in the downstream sleeve66, a high resistance to the flow of the material from the radiallyoutermost flow passages 26 is encountered. To alleviate the highresistance to the flow of the material and to preclude undesiredcollection of the material in the radially outermost area, the radiallyoutermost row of apertures are oriented to direct the flow of materialmore inwardly.

Accordingly, around the perimeter of the breaker plate 24 the outermostrow of flow passages 104 is disposed at an angle with respect to thelongitudinal axis of the breaker plate. Each of these flow throughpassages 104 are angled inwardly from the upstream side to thedownstream side so that the flow of material is directed radiallyinwardly as well. Since these apertures are longer, increased flowresistance results. Accordingly, a V-groove 102 is provided on thedownstream side of flow passages 104 to shorten the flow path formaterial passing through these passages. The flow passages 104 feedmaterial into the cavity 70 at its outermost periphery and because ofthe angle of inclination of the outermost passages the flow of materialis directed more inwardly to closely assume the contour of the cavity 70in the sleeve 66 and thus a minimum of flow restriction results.

While the specific embodiment disclosed herein illustrates a breakerplate carried within a slide plate, it is also to be understood that thepresent invention may also be utilized where the breaker plateconfiguration is formed directly in a slide plate as an integral unit.In this case the flow passages and 104 would be drilled through theslide plate itself and the sealing sleeve would bear against the slideplate radially outwardly of the breaker plate configuration.

It is thus seen that the present invention provides an improvedconstruction for slide plate screen changers which provides a simple andeffective manner of sealing the slide plate passage to precludeundesired leakage of material. The invention also provides an improvedbreaker plate construction which minimizes flow resistance of materialflowing through the breaker plate flow passages.

I claim:

1. An apparatus to filter contaminants from a heatsoftened materialcomprising,

a housing,

said housing including a first passage therethrough through which saidheat-softened material is forced to flow,

said housing including a second passage therethrough intersecting saidfirst passage,

a slide plate disposed within said second passage,

said slide plate including an opening therein disposed in register withsaid first passage in said housing,

filter means disposed within said opening in said slide plate to filtersaid heat-softened material flowing through said first passage,

a sleeve member having an axial passage therethrough disposed withinsaid first passage on the upstream side of said slide plate,

said sleeve member having one end thereof disposed in sealingrelationship with said opening in said slide plate and having its otherend extending beyond the surface of said housing, and

means disposed exterior said housing adapted to contact said sleevemember other end and impart sealing force thereto to insure sealingbearing of said sleeve member one end with said slide plate.

2. Apparatus as defined in claim 1 wherein said means disposed exteriorsaid housing comprises an adapter member provided with a passagetherethrough in register with said axial passage of said sleeve memberand including a radially outwardly extending flange segment thereabout,means engageable between said flange segment and said housing to applyinward sealing force against said sleeve member.

3. Apparatus as defined in claim 2 wherein said flange segment includesa plurality of circumferentially spaced bolt receiving aperturestherethrough, said housing including a plurality of threaded boltreceiving bores in register with said bolt receiving apertures in saidflange segment and said means engageable between said flange segment andsaid housing comprise a plurality of bolt members disposed through saidbolt receiving apertures and threadably engaged within said boltreceiving bores whereby sealing force is obtained by threaded engagementof said bolts within said bores to exert bearing pressure against saidsleeve member.

4. Apparatus as defined in claim 3 wherein said sleeve member other endextends beyond the surface of said housing and said adapter memberincludes an indentation formed in the end disposed adjacent saidhousing, said indentation being dimensioned to receive the extendingportion of said sleeve member other end therein whereby said adaptermember engages and bears against said sleeve member to provide saidsealing force.

5. Apparatus as defined in claim 1 wherein a second sleeve member isprovided within said first passage on the downstream side of said slideplate, said second sleeve member having one end thereof disposed insealing relationship with said opening in said slide plate and havingits other end extending beyond the surface of said housing, and meansdisposed exterior said housing adapted to contact said second sleevemember other end and import sealing force thereto to insure sealingbearing of said second sleeve member one end with said slide plate.

6. Apparatus as defined in claim 5 wherein said second sleeve memberincludes flow passage means therethrough and said means disposedexterior said housing comprises an adapter member provided with apassage therethrough in register with said flow passage means of saidsecond sleeve member and a radially outwardly extending flange segmentthereabout, means engageable between said flange segment and saidhousing to apply inward sealing force against said sleeve member toinsure sealing bearing of said second sleeve member one end with saidslide plate.

7. Apparatus as defined in claim 5 wherein said filter means comprises afilter medium of mesh-like material supported on its downstream side bya breaker plate comprising a plate member provided with a plurality offlow passages therethrough and said passage means in said second sleevemember comprises a cavity formed in said one end of said second sleevemember having a conical shape terminating in an axially disposed flowpassage to said second sleeve member other end whereby material flowsthrough said filter medium and breaker plate into said cavity and outsaid flow passage.

8. Apparatus as defined in claim 7 wherein the radially innermost onesof said plurality of flow passages provided in said breaker plate areoriented with their axes parallel to the flow path of material throughsaid housing and the radially outermost ones of said plurality of flowpassages provided in said breaker plate are oriented with their axesdirected inwardly in the direction of material flow to channel the flowof material to more nearly conform to the configuration of said cavityin said second sleeve member thereby to minimize flow resistance.

1. An apparatus to filter contaminants from a heat-softened materialcomprising, a housing, said housing including a first passagetherethrough through which said heat-softened material is forced toflow, said housing including a second passage therethrough intersectingsaid first passage, a slide plate disposed within said second passage,said slide plate including an opening therein disposed in register withsaid first passage in said housing, filter means disposed within saidopening in said slide plate to filter said heat-softened materialflowing through said first passage, a sleeve member having an axialpassage therethrough disposed within said first passage on the upstreamside of said slide plate, said sleeve member having one end thereofdisposed in sealing relationship with said opening in said slide plateand having its other end extending beyond the surface of said housing,and means disposed exterior said housing adapted to contact said sleevemember other end and impart sealing force thereto to insure sealingbearing of said sleeve member one end with said slide plate. 2.Apparatus as defined in claim 1 wherein said means disposed exteriorsaid housing comprises an adapter member provided with a passagetherethrough in register with said axial passage of said sleeve memberand including a radially outwardly extending flange segment thereabout,means engageable between said flange segment and said housing to applyinward sealing force against said sleeve member.
 3. Apparatus as definedin claim 2 wherein said flange segment includes a plurality ofcircumferentially spaced bolt receiving apertures therethrough, saidhousing including a plurality of threaded bolt receiving bores inregister with said bolt receiving apertures in said flange segment andsaid means engageable between said flange segment and said housingcomprise a plurality of bolt members disposed through said boltreceiving apertures and threadably engaged within said bolt receivingbores whereby sealing force is obtained by threaded engagement of saidbolts within said bores to exert bearing pressure against said sleevemember.
 4. Apparatus as defined in claim 3 wherein said sleeve memberother end extends beyond the surface of said housing and said adaptermember includes an indentation formed in the end disposed adjacent saidhousing, said indentation being dimensioned to receive the extendingportion of said sleeve member other end therein whereby said adaptermember engages and bears against said sleeve member to provide saidsealing force.
 5. Apparatus as defined iN claim 1 wherein a secondsleeve member is provided within said first passage on the downstreamside of said slide plate, said second sleeve member having one endthereof disposed in sealing relationship with said opening in said slideplate and having its other end extending beyond the surface of saidhousing, and means disposed exterior said housing adapted to contactsaid second sleeve member other end and import sealing force thereto toinsure sealing bearing of said second sleeve member one end with saidslide plate.
 6. Apparatus as defined in claim 5 wherein said secondsleeve member includes flow passage means therethrough and said meansdisposed exterior said housing comprises an adapter member provided witha passage therethrough in register with said flow passage means of saidsecond sleeve member and a radially outwardly extending flange segmentthereabout, means engageable between said flange segment and saidhousing to apply inward sealing force against said sleeve member toinsure sealing bearing of said second sleeve member one end with saidslide plate.
 7. Apparatus as defined in claim 5 wherein said filtermeans comprises a filter medium of mesh-like material supported on itsdownstream side by a breaker plate comprising a plate member providedwith a plurality of flow passages therethrough and said passage means insaid second sleeve member comprises a cavity formed in said one end ofsaid second sleeve member having a conical shape terminating in anaxially disposed flow passage to said second sleeve member other endwhereby material flows through said filter medium and breaker plate intosaid cavity and out said flow passage.
 8. Apparatus as defined in claim7 wherein the radially innermost ones of said plurality of flow passagesprovided in said breaker plate are oriented with their axes parallel tothe flow path of material through said housing and the radiallyoutermost ones of said plurality of flow passages provided in saidbreaker plate are oriented with their axes directed inwardly in thedirection of material flow to channel the flow of material to morenearly conform to the configuration of said cavity in said second sleevemember thereby to minimize flow resistance.